#18899 FileSystemStorage.save should support any file-like objects
Fixed regression introduced in 146ed13a.

As override_settings was used after the initialization of the session backend,
we need to use a new session backend here.
Merge pull request #775 from HiddenData/ticket-18899

Fixed #18899 -- FileSystemStorage.save should support any file-like objects
Updated example to use staticfiles static template tag, thanks reinout for the suggestion, refs #19675.
Merge pull request #777 from khalas/ticket_19811

Fixed #19811 - Added language code fallback in get_language_info
Fixed #19827 -- Kept stacktrace in defaulttags exception reraising

Thanks Kronuz for the report and the initial patch.
Minor cleanups in templates test imports
Added test runner option to skip Selenium tests (#19854).
Merge pull request #781 from zsiciarz/ticket_19854

Fixed #19854 -- Added test runner option to skip Selenium tests
Fixed #15877 -- Improved exception when ModelForm has no model class

Thanks theaspect at gmail.com for the report and volrath for the
patch.
Changed %r to %s in get_language_info error message.